Recently, there has been a rapid increase in the use of video display terminals (VDT's) and the like. It has been shown that the surface of the cathode ray tube (CRT) in a VDT reflects glare from the surrounding environment which, in many instances, causes the user to experience eye fatigue and headache. A framed mesh screen of black filaments disclosed in U.S. Pat. No. 4,253,737 has been introdueced to overcome the glare problem.
A potentially more serious problem with VDT's is their tendency to generate an electrostatic field adjacent to the CRT. This problem has recently been classified as a potential health hazard. In fact, many facial rash cases amount VDT operators have been reported. This is attributable to the operator becoming electrically charged in the electrostatic field of the CRT so that dust and other pollutants, such as bacteria or other irritants, of opposite charge are attracted to the operator. The dust carrying opposite charge may also be attracted to the surface of the CRT and pollute the VDT screen as a result of the induced static charge. The risk of nonionizing radiation in VDT screens that has been debated for several years. It was reported that current levels of electromagnetic radiation which emanate from the CRT are well below the level at which the operator may become injured. However, such radiation does exist and older VDT's and those in a worsened condition most likely will produce radiation at levels which exceed the FDA standard allowed for television sets. At present, low frequency radiation is eleiminated by a stainless steel (or other metal) mesh screen sandwiched between to rigid panels placed in front of the VDT screen. Due to the space between the screens and the display tubes, such devices produce Newton rings and Morie distortions. Mesh screens designed to eliminate such distortions are shown in U.S. Pat. Nos. 4,253,737 and 4,468,702.
As disclosed above, the screen of U.S. Pat. No. 4,253,737 was introduced to overcome the glare problems. The nylon screen disclosed in U.S. Pat. No. 4,468,702 is formed of a plurality of nylon yarns, some of which are electrically conductive. However, the method of making this screen is quite complicated and produces screen where only a fraction of the warp and weft fibers of the screen are electrically conductive. As disclosed of U.S. Pat. No. 4,760,456 was introduced, a conductive screen formed of a frame and a series of electrically conductive fibers. The screen is fitted over the display surface of a cathode ray tube (CRT) and connected to a ground wire to diffuse emanated radiation and static electricity.